We propose a series of experiments to study the relationship between body weight and feeding in the Rhesus monkey. We plan to observe this relationship in situations of low body weight (fasting), high body weight (force-fed) and in the dynamic and static phases of hypothalamic obesity. As well as documenting feeding changes and correlating them with body weight deviations, we are measuring blood glucose, cholesterol, triglycerides, free fatty acids, radioimmuno active insulin and glucagon during these events and attempting to correlate changes in these body constituents with feeding and body weight. Direct efforts to manipulate these blood constituents will be made in experiments feeding median chain triglycerides to normal and hypothalamically obese monkeys to produce ketonemia and in experiments on the effect of vagotomy on hypothalamic hyperphagia. The objective is to document the correlations between feeding and body weight and to search for hormonal or metabolic events that might link the neural mechanisms for feeding to the stores of body nutrient. BIBLIOGRAPHIC REFERENCES: McHugh, P. R., Moran, T., Gibbs, J., and Falasco, J. Intragastric Nutrient Infusions and Caloric Satiety in Monkeys. Federation Proceedings, Volume 34, No. 3 p. 374, 1975. McHugh, P. R., Moran, T. H., and Barton, G. A Graded Behavioral Phenomenon Regulating Caloric Intake. Science, 190, p. 167-69, 1975.